Method of manufacturing power semiconductor device

ABSTRACT

A method of manufacturing a power semiconductor device includes forming trenches in a substrate, wherein the substrate includes a first surface and a second surface opposite to the first surface, forming a gate insulating layer and a gate electrode in each of the trenches, forming a P-type base region between the trenches in the substrate, performing a first implantation process using P-type dopants implanted onto the P-type base region, forming an N+ source region in the substrate, forming an interlayer insulating layer on the N+ source region, performing a second implantation process using P-type dopants to form a P+ doped region on the P-type base region, forming an emitter electrode in contact with the N+ source region and the P+ doped region, forming a P-type collector region on the second surface of the substrate, and forming a drain electrode on the P-type collector region.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/686,874 filed on Aug. 25, 2017, which claims the benefit under 35 USC119(a) of Korean Patent Application No. 10-2017-0030500 filed on Mar.10, 2017 in the Korean Intellectual Property Office, the entiredisclosures of which are incorporated herein by reference for allpurposes.

BACKGROUND 1. Field

The following description relates to a method of manufacturing a powersemiconductor device. The following description also relates to a methodof manufacturing a power semiconductor device that manages breakdownvoltage effectively and reduces gate capacitance by reducing the powerof an electric field (E-field) compared to an alternative powersemiconductor device by the improvement of a structure of an InjectionEnhanced Gate Transistor (IEGT) and, accordingly, reduces energyconsumption and improves the performance of switching.

2. Description of Related Art

In the field of power electronics, there is a strong demand forminiaturization and high performance of power supply devices. To meetthese demands, power semiconductor devices have been improved inperformance for providing low loss and low noise as well as to be ableto withstand high voltage and large currents. Under such circumstances,an IEGT that is made by improving an Insulated Gate Bipolar Transistor(IGBT) has been attracting attention as a device having a low ON voltagecharacteristic and being capable of reducing a turn-off losssimultaneously.

In particular, in order to secure a Breakdown Voltage Collector-Emitter,specified with a zero gate emitter voltage (BV_(CES)) of an IEGT,alternative technologies recently publicized minimize a floatinginterval of the IEGT or increase a resistivity value of an Epi layer andsecure the BV_(CES) that is the breakdown voltage between the collectorand the emitter.

However, such alternative technologies have had problems of increasingCollector-Emitter Saturation Voltage (V_(ce)(sat)) by reducing afloating effect or of reducing switching performance by increasing thethickness of the Epi Layer.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

In one general aspect, a method of manufacturing a power semiconductordevice includes forming trenches in a substrate, wherein the substrateincludes a first surface and a second surface opposite to the firstsurface, forming a gate insulating layer and a gate electrode in each ofthe trenches, forming a P-type base region between the trenches in thesubstrate, performing a first implantation process using P-type dopantsimplanted onto the P-type base region, forming an N+ source region inthe substrate, forming an interlayer insulating layer on the N+ sourceregion, performing a second implantation process using P-type dopants toform a P+ doped region on the P-type base region, forming an emitterelectrode in contact with the N+ source region and the P+ doped region,forming a P-type collector region on the second surface of thesubstrate, and forming a drain electrode on the P-type collector region.

The method of manufacturing a power semiconductor device may furtherinclude forming a floating region and an N-type well region in thesubstrate.

The substrate may include a high-concentration first epitaxial-layer anda low-concentration second epitaxial-layer.

The P+ doped region may have a greater depth than a depth of the N+source region.

The N+ source region and the P+ doped region may each contact a sidewallof the emitter electrode.

The method of manufacturing a power semiconductor device may furtherinclude performing a rapid thermal process after performing the firstimplantation process, and performing a grinding process on the secondsurface of the substrate, before forming the collector region.

An ion implantation energy of the first implantation process may begreater than an ion implantation energy of the second implantationprocess.

A dose amount of the second implantation process may be smaller than adose amount of the first implantation process.

The interlayer insulating layer may include two stacked layers.

A first layer of the interlayer insulating layer may be a Chemical VaporDeposition (CVD) oxide layer, and a second layer of the interlayerinsulating layer may be one of phosposilicate glass (PSG) andborophosphosilicate glass (BPSG).

The emitter electrode may be formed of aluminum (Al), copper (Cu), or analuminum/copper (Al/Cu) alloy.

In another general aspect, a method of manufacturing a powersemiconductor device includes forming trenches in a substrate includinga first surface and a second surface opposite to the first surface,forming a gate insulating layer and a gate electrode in each of thetrenches, forming a P-type base region in the substrate, forming a P+doped region and a N+ source region in the P-type base region, formingan interlayer insulating layer on the P+ doped region and the N+ sourceregion, forming an interlayer insulating layer pattern on the gateelectrode, and subsequently performing a compensation process, formingan emitter electrode contacting the N+ source region, forming acollector region on the second surface of the substrate, and forming adrain electrode on the collector region.

The method of manufacturing a power semiconductor device may furtherinclude performing a rapid thermal process after forming the P+ dopedregion.

The compensation process may include performing an implantation process,using P-type dopants, into the P+ doped region.

A portion of the P+ doped region contacting a sidewall of the emitterelectrode may be larger than a portion of the N+ source regioncontacting the sidewall of the emitter electrode.

The interlayer insulating layer may include two stacked layers.

A first layer of the interlayer insulating layer may be a Chemical VaporDeposition (CVD) oxide layer, and a second layer of the interlayerinsulating layer may be one of phosposilicate glass (PSG) andborophosphosilicate glass (BPSG).

The emitter electrode may be formed of aluminum (Al), copper (Cu), or analuminum/copper (Al/Cu) alloy.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a power semiconductor device according to anexample.

FIG. 2 is a flow chart of a power semiconductor device according to anexample.

FIGS. 3 to 10 are drawings illustrating a power semiconductor deviceaccording to an example.

FIG. 11 is a result of a device simulation of a power semiconductordevice manufactured by alternative technology.

FIG. 12 is a result of a device simulation of a power semiconductoraccording to an example.

FIG. 13 is a Scanning Electron Microscope (SEM) picture of a powersemiconductor according to an example.

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements. The drawings may not be to scale,and the relative size, proportions, and depiction of elements in thedrawings may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the methods, apparatuses, and/orsystems described herein will be apparent after an understanding of thedisclosure of this application. For example, the sequences of operationsdescribed herein are merely examples, and are not limited to those setforth herein, but may be changed as will be apparent after anunderstanding of the disclosure of this application, with the exceptionof operations necessarily occurring in a certain order. Also,descriptions of features that are known in the art may be omitted forincreased clarity and conciseness.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided merelyto illustrate some of the many possible ways of implementing themethods, apparatuses, and/or systems described herein that will beapparent after an understanding of the disclosure of this application.

Throughout the specification, when an element, such as a layer, region,or substrate, is described as being “on,” “connected to,” or “coupledto” another element, it may be directly “on,” “connected to,” or“coupled to” the other element, or there may be one or more otherelements intervening therebetween. In contrast, when an element isdescribed as being “directly on,” “directly connected to,” or “directlycoupled to” another element, there can be no other elements interveningtherebetween.

As used herein, the term “and/or” includes any one and any combinationof any two or more of the associated listed items.

Although terms such as “first,” “second,” and “third” may be used hereinto describe various members, components, regions, layers, or sections,these members, components, regions, layers, or sections are not to belimited by these terms. Rather, these terms are only used to distinguishone member, component, region, layer, or section from another member,component, region, layer, or section. Thus, a first member, component,region, layer, or section referred to in examples described herein mayalso be referred to as a second member, component, region, layer, orsection without departing from the teachings of the examples.

Spatially relative terms such as “above,” “upper,” “below,” and “lower”may be used herein for ease of description to describe one element'srelationship to another element as shown in the figures. Such spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. For example, if the device in the figures is turned over,an element described as being “above” or “upper” relative to anotherelement will then be “below” or “lower” relative to the other element.Thus, the term “above” encompasses both the above and below orientationsdepending on the spatial orientation of the device. The device may alsobe oriented in other ways (for example, rotated 90 degrees or at otherorientations), and the spatially relative terms used herein are to beinterpreted accordingly.

The terminology used herein is for describing various examples only, andis not to be used to limit the disclosure. The articles “a,” “an,” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. The terms “comprises,” “includes,”and “has” specify the presence of stated features, numbers, operations,members, elements, and/or combinations thereof, but do not preclude thepresence or addition of one or more other features, numbers, operations,members, elements, and/or combinations thereof.

Due to manufacturing techniques and/or tolerances, variations of theshapes shown in the drawings may occur. Thus, the examples describedherein are not limited to the specific shapes shown in the drawings, butinclude changes in shape that occur during manufacturing.

The features of the examples described herein may be combined in variousways as will be apparent after an understanding of the disclosure ofthis application. Further, although the examples described herein have avariety of configurations, other configurations are possible as will beapparent after an understanding of the disclosure of this application.

Expressions such as “first conductivity type” and “second conductivitytype” as used herein may refer to opposite conductivity types such as Nand P conductivity types, and examples described herein using suchexpressions encompass complementary examples as well. For example, anexample in which a first conductivity type is N and a secondconductivity type is P encompasses an example in which the firstconductivity type is P and the second conductivity type is N.

Hereinafter, examples are described in detail with reference to theaccompanying drawings.

In the method of manufacturing power semiconductor device according toexamples, the ion implantation energy and dose amount of the formationof the second P+ doped region are smaller than the ion implantationenergy and dose amount used for forming the first P+ doped region.

The method of manufacturing power semiconductor device according to theexamples is directed to providing a semiconductor device that canprovide low V_(ce)(sat) and an improved switching performance without areduction of BV_(CES) by reducing an electric field concentrated on theunderside of the trench structure by forming a floating region deeperthan usual to encompass the underside of the trench structure.

Thus, this disclosure is provided to introduce a method of manufacturinga power semiconductor device that is able to maintain BV_(CES), reducegate capacitance, and accordingly provide improved switching performancewith less power energy consumption.

Hereinafter, in FIG. 1 to FIG. 12, a method of manufacturing a powersemiconductor device according to an example and a power semiconductordevice manufactured thereby are described in further detail.

FIG. 1 is a top view of a power semiconductor device according to anexample.

The power semiconductor device includes tens and hundreds of active cellregions 205. One unit active cell region 205 includes N+ source region230 and a P+ doped region 235, wherein the N+ refers to a high dopingconcentration of N-type dopants, and P+ also refers to a high dopingconcentration of P-type dopants. In such an example, the N+ sourceregion 230 surrounds the P+ doped region 235. Also, the powersemiconductor device includes trench gate structures 210 surrounding theN+ source region 230 and the P+ doped region 235. A P-type floatingregion (DF) 220 is formed between each of the trench gate structures 210and the other trench gate structures 210. The floating region 220 is notelectrically connected to the emitter electrode or the gate electrode,and is thus entirely in a floating state.

FIG. 2 is a flow diagram for fabrication of a power semiconductor deviceaccording to an example. At operation S10, a substrate including a firstepitaxial-layer 250 and a second epitaxial-layer 252 is prepared. Thesecond epitaxial-layer is used as electric field stop layer. In theexample of FIG. 2, the first epitaxial-layer is used as a drift region.At operation S20, a floating region and an N-type well region are formedin the first epitaxial-layer. At operation S30, trenches are formed inthe substrate and a gate insulating layer and a gate electrode areformed in each of the trenches. At operation S40, a P-type base regionis formed in the substrate. Operation S50 is a first implantationprocess to form a P+ doped region. At operation S60, an N+ source regionis formed. Operation S70 is a contact formation process to open a topsurface of the substrate. Operation S80 is a compensation process tocompensate P-type dopants in the P+ doped region using a secondimplantation process. In further detail, operation S80 is an operationof forming a second P+ doped region in the first P+ doped region. In anexample, the ion implanting energy and dose amount of forming the secondP+ doped region are smaller than the ion implanting energy and doseamount of forming the first P+ doped region.

At operation S90, an emitter electrode and a passivation layer areformed. The emitter electrode contacts the N+ source region and the P+doped region. Also, at operation S100, a back side grinding operation isperformed on the rear surface of the substrate to remove a portion ofthe substrate until the N+ field stop layer is exposed. Additionally, aP+ collector layer 257 is formed. Furthermore, a power semiconductordevice is completed by forming a drain electrode 259.

First, as illustrated in the example of FIG. 3, the substrate 100includes a first epitaxial-layer 252 doped with high-concentrationN-type dopant and a second epitaxial-layer 250 doped withlow-concentration N-type dopant on the base substrate 254. In such anexample, two epitaxial-layers 252, 250 having different concentrationsfrom each other are formed. In this example, the first epitaxial-layer252 with a high concentration of impurities operates as a field stoplayer, or a buffer layer, as shown in FIGS. 9-10, with reference tobuffer layer 255. The second epitaxial-layer 250 operates as a driftregion 250, which is explained further hereinafter.

The thickness of the second epitaxial-layer 250 may be 90˜100 um. Areason for forming the second epitaxial-layer 250 to be thick in thismanner is to separate the floating region 220 from the firstepitaxial-layer 252, which will be formed subsequently, by apredetermined distance. Through this approach of using the specifiedthicknesses, it becomes possible to increase breakdown voltage for thepower semiconductor device by securing a certain distance between thefirst epitaxial-layer 252 and the base region 240 or the floating region210.

Then, as illustrated in the example of FIG. 4, a P-type floating regionDF 220, a Local Oxidation of Silicon (LOCOS) layer 260 and an N-typewell region 245 are formed in the substrate.

More specifically, floating mask patterns are formed to be separatedapart at regular intervals on the substrate. Also, floating regions 220are formed by ion implantation of a P-type dopant in the substrate. Forexample, as such a P-type dopant, boron (B) or boron difluoride (BF2)may be used. However, these are only examples, and other P-type dopantsare used in other examples. For example, the floating regions 220 areformed to have a depth of 8-9 um. With respect to securing the breakdownvoltage, the depth of the floating region 220 is potentially about 8 to10% of the thickness of the N-type drift region 250. For example, thefloating region 220 may be formed with a greater depth as compared tothe well region 245.

A LOCOS 260 region is formed in the substrate 100. This LOCOS 260 regionis used to separate a plurality of active cell regions. Also, in anexample, an N-type well region 245 is formed between the floatingregions 220. For example, the well region 245 is formed to have athickness of 6-7 um measured from the upper side of the substrate.

Such an N-type well region 245 takes on a role of inhibiting the holecarrier from moving to the N+ source region 230 from the drain metallayer or electrode 259. In an example, for this purpose, the N-type wellregion 245 is formed to have a higher concentration of impuritiescompared to the N-type drift region 240. Accordingly, when hole carriersaccumulate in the drift region 140, conductivity modulation morefrequently happen by the increase of the electron carriers and, as aresult, resistance lowers. Therefore, the electron carriers are able toeasily move into the drain region even at a small voltage, therebyachieving a low Vce (sat) characteristic.

Also, as illustrated in the example of FIG. 5, trenches 211, 212, 213,and 214 are formed at a predetermined depth from the upper surface ofthe substrate. For example, the trenches 211, 212, 213, 214 arerespectively formed to be in contact with the sides of the floatingregions 220 and the well region 245. Subsequently, for convenience ofexplanation, the trenches are respectively referred to as the firsttrench 211, the second trench 212, the third trench 213, and the fourthtrench 214 as left to right in the drawing. For example, the trenches,from the first trench to the fourth trench 211, 212, 213, 214 may beformed by the etching process on the semiconductor substrate, and eachis formed to have an identical depth with one another through anidentical process.

A gate insulating layer 216 and a gate electrode 215 are respectivelyformed inside of each of the trenches 211, 212, 213, 214. The gateelectrode 216 is formed by depositing and patterning poly-silicon, whichis a conductive material.

Sequentially, as illustrated in the example FIG. 5, photo mask patternsare formed in the substrate, and a P-type base region 240 is formed byselectively ion implantation a P-type dopant using a mask pattern withinan N-type well region 245. Accordingly, the area of the N-type wellregion 245 is reduced. Also, an annealing process at a high temperature,such as 700° C. to 900° C., may be performed to extend the P-type baseregion in the downward direction of the substrate.

FIG. 6 shows a first implantation process using P-type dopants over theP-type base region. P+ mask patterns 120 are formed on the substrate toform P+ doped region 235. The P+ mask patterns 120 are formed on thegate electrodes 215 and accordingly the substrate is exposed. The firstP+ doped region 235 are formed through a first implantation process 285using a P-type dopant. For example, boron may be used as the P+ dopant,but other appropriate dopants are used in other examples. In an example,the ion implantation process is performed using a boron dopant at an ionimplantation energy between 100-200 KeV and a dose between1E14-1E16/cm². After forming the first P+ doped region 235, a rapidthermal process (RTP) is performed to activate the P+ dopants. Thus, RTPis one of the activation processes. In an example, RTP is performed at ahigh temperature, such as a temperature in a range from 850° C. to 1200°C., for 10 to 120 seconds.

As illustrated in the example of FIG. 7, the N+ source region 230 isformed. For example, the N+ source region 230 is formed by selective ionimplantation using an N-type dopant in the substrate. In such anexample, a depth of the N+ source region is shallower than a depth ofthe first P+ doped region 235.

For example, an alternative process may have the following sequence.First, the N+ source region 230 is formed and then a P+ doped region isformed. An activation process such as RTP is applied. In that example,the N-type dopants diffuse into the P+ doped region in a large quantity.Accordingly, an area of the P+ doped region is able to be reduced. Also,in this example, enough of a safety operation area (SOA) is unable to besecured. However, as in an example of the present disclosure, when rapidthermal annealing (RTA) is performed immediately after the firstimplantation process, the diffusion of the N-type dopants into the P+doped region is suppressed. By using such an approach, the P+ dopedregion is secured to some extent. Accordingly, a sufficient operationarea is able to be secured.

As illustrated in the example of FIG. 8, on the upper surface of thesubstrate, a thick interlayer insulating layer 270 is deposited by aChemical Vapor Deposition (CVD) method. Thus, an insulating layer 270 ofsilicon oxide series is used as an interlayer insulating layer. Forexample, the insulating layer 270 may comprise stacked two layers. Thefirst layer may be CVD oxide layer, and the second layer may be one ofphosphosilicate glass (PSG) or borophosphosilicate glass (BPSG)materials. However, these are only example materials and alternativematerials with similar properties are potentially used in otherexamples. However, the PSG or BPSG material has good flowcharacteristics, and therefore, the interlayer insulating layer 270 isable to be flattened. This approach is used because forming theinterlayer insulating layer 270 to be flattened is necessary to form acontact mask pattern. Also, the contact mask pattern 140 is formed onthe interlayer insulating layer 270. By using such a contact maskpattern 140 as a mask, a contact etching process for etching a portionof the interlayer insulating layer 270 is also performed.

FIG. 9 shows a second implantation process using P-type dopants to forma P+ doped region in the P-type base region. Through the contact etchingprocess, an insulating layer pattern 270 is formed over the gateelectrode 215. A top surface or first surface of the substrate 100,including P+ doped region 235, is exposed. Namely, the exposed substratehas a P+ doped region 235. A top portion of the P+ doped region isremoved slightly during the contact etching process. Accordingly, a topportion of the first P+ doped region 235 is etched. As a result, theentire thickness of the first P+ doped region 235 becomes thinner, andthe area of the P+ doped region 235 is slightly decreased. Due to thisprocessing, the doping concentration of the P+ doped region 235decreases.

Therefore, to compensate for the changes to the doping concentration ofthe P+ doped region 235, a second implantation process 295 using P-typedopants is performed as illustrated in the example of FIG. 9. Thereduced amount of P-type dopant is compensated for through performingthe second implantation process 295. The compensation process includes asecond implantation process 295 using P-type dopants into the first P+doped region. Accordingly, the doping concentration of the first dopedregion is increased. For example, the second implantation process 295 isperformed using BF dopants with implantation energy less than 100 KeVand an implantation dose ranged from 1E14 to 1E16/cm². However, theseare only examples and other appropriate dopants and implantationparameters may be used, as appropriate, in other examples. The dose andion implantation energy of the second implantation process 295 are smallas compared to the first implantation process 285. Therefore, it ispossible to state that a second P+ doped region is formed in the firstP+ doped region by a second implantation process 295.

Also, an annealing process is performed at a temperature below 900° C.after the second implantation process. Such an annealing process curesetch damage of the substrate caused by the contact etching process.Diffusion of N+ dopants is negligible during this annealing process.

As illustrated in the example of FIG. 10, an emitter electrode 280 isformed on the insulating layer pattern 270 and a substrate 100 using ametallic material such as aluminum (Al), copper (Cu), or an Al/Cu alloy.However, these are only examples and other appropriate metallicmaterials with similar properties are used in other examples. Theemitter electrode 280 and the gate electrode 215 are electricallyseparated from each other by the presence of the insulating layerpattern 270. The N+ source region 230 and the P+ doped region 235 areelectrically connected to the emitter electrode 280.

Furthermore, a passivation layer 290 is formed in order to preventmoisture and other potentially detrimental material from penetratinginto the semiconductor device after forming the emitter electrode. Also,a backside grinding process is performed on the back side or secondsurface of the substrate. Through the backside grinding process, a basesubstrate 254 is eliminated. When the base substrate 254 is eliminated,the backside grinding process is performed until the firstepitaxial-layer 252 is exposed. The remaining first epitaxial-layer 252becomes an N+ field stop layer 255 as a result. Therefore, there is anattendant advantage of this example that a separate ion implantationprocess for forming the N+ field stop layer 255 is not necessary.

The field stop layer 255 acts to prevent the electric field formed fromthe emitter electrode from extending further to the P+ collector layer257. In the absence of the field stop layer 255, the thickness of thedrift region 250 must be made to be very thick, in which case theresistance is increased by the presence of a drift region 250 doped witha low concentration of dopant. Also, in the absence of the field stoplayer 255, the electric field is formed to extend deeper downward andthe PN diode is unable to be formed, so that the IGBT function used fora high-capacity current is unable to be exhibited properly.

Next, a P+ collector layer 257 is formed. Finally, a powersemi-conductor device is completed by depositing a drain electrode 259.

FIGS. 11 and 12 are device simulation results shown to explain andillustrate the difference between the alternative technology and thepresent examples. FIG. 11 illustrates an example of being manufacturedby an alternative process, and FIG. 12 corresponds to an example.

When the manufacturing process is performed by an alternative process,as shown in FIG. 11 at (A) and (B), the arrows shown in FIG. 11 areformed to be deeper in the N+ source region 230 than the P+ doped region235. In particular, the P+ doped region 235 is formed to be shallower.Also, it can be observed that sidewall 280 a of the emitter electrode280 mainly is in contact with the N+ source region 230. Because theconcentration of the N-type dopants is locally greater than that of theP-type dopants at the bottom corner of the emitter electrode, the boronis displaced by phosphorous, which is an N-type dopant. The N-typedopants diffuse toward to the bottom corner of the emitter contactelectrode. Therefore, it may be impossible to obtain a Reverse BiasSafety Operation Area (RBSOA) in the reverse bias state in thealternative technology due to its vulnerability to the dynamic latch-up.The RBSOA parameter is relevant to testing stable operating conditionsin the turn-off state in the IGBT device.

However, in the present examples, as illustrated in FIG. 12 at (A) and(B), the N+ source region 230 is formed to be shallower than the P+doped region 235. Accordingly, a desirable P+ doped region 235 issecured. A portion of the P+ doped region contacting the sidewall of theemitter electrode is larger than a portion of the N+ source regioncontacting the sidewall of the emitter electrode. It can be seen in theexample of FIG. 12 that the N+ source region 230 and the P+ doped region235 simultaneously contact the sidewall 280 a of the emitter electrode280. After activating the P+ type dopant followed by the N+ type dopant,a stable P+ region is secured at the bottom corner of the emittercontact 280. Therefore, dynamic latch-up performance is improved. Also,five times an RBSOA level is able to be secured. As a result of an SOAtest, good results were obtained under all evaluation conditions, and nosignificant difference was noted for the various RTP conditions.

FIG. 13 is an SEM picture of a power semiconductor according to anexample. As illustrated in the drawing, N+ source region and P+ dopedregion are clearly illustrated. It may also be seen that the SEM pictureis almost identical to the result of device simulation.

The method of manufacturing a power semiconductor device according tothe present examples provides a method of manufacturing a powersemiconductor device capable of securing a P+ doped region with adesired design and providing a wide RBSOA window, through the abovetechnical construction.

While this disclosure includes specific examples, it will be apparentafter an understanding of the disclosure of this application thatvarious changes in form and details may be made in these exampleswithout departing from the spirit and scope of the claims and theirequivalents. The examples described herein are to be considered in adescriptive sense only, and not for purposes of limitation. Descriptionsof features or aspects in each example are to be considered as beingapplicable to similar features or aspects in other examples. Suitableresults may be achieved if the described techniques are performed in adifferent order, and/or if components in a described system,architecture, device, or circuit are combined in a different manner,and/or replaced or supplemented by other components or theirequivalents. Therefore, the scope of the disclosure is defined not bythe detailed description, but by the claims and their equivalents, andall variations within the scope of the claims and their equivalents areto be construed as being included in the disclosure.

What is claimed is:
 1. A power semiconductor device, comprising:trenches in a substrate, wherein the substrate comprises a first surfaceand a second surface opposite to the first surface; a gate insulatinglayer and a gate electrode in each of the trenches; a P-type base regionbetween the trenches in the substrate; an N+ source region in thesubstrate; a P+ doped region on the P-type base region; an interlayerinsulating layer on the N+ source region; and an emitter electrode incontact with the N+ source region and the P+ doped region, wherein theN+ source region and the P+ doped region each contact a verticalsidewall of the emitter electrode.
 2. The power semiconductor device ofclaim 1, further comprising: a floating region in the substrate, whereinthe floating region has a depth deeper than a depth of the P-type baseregion.
 3. The power semiconductor device of claim 1, wherein thesubstrate comprises a high-concentration first epitaxial-layer and alow-concentration second epitaxial-layer.
 4. The power semiconductordevice of claim 1, wherein the P+ doped region has a greater depth thana depth of the N+ source region.
 5. The power semiconductor device ofclaim 1, wherein the interlayer insulating layer comprises two stackedlayers.
 6. The power semiconductor device of claim 5, wherein a firstlayer of the interlayer insulating layer is a Chemical Vapor Deposition(CVD) oxide layer, and a second layer of the interlayer insulating layeris one of phosphosilicate glass (PSG) and borophosphosilicate glass(BPSG).
 7. The power semiconductor device of claim 1, furthercomprising: a P-type collector region on the second surface of thesubstrate; and a drain electrode on the P-type collector region.
 8. Thepower semiconductor device of claim 1, wherein a portion of the P+ dopedregion contacting a vertical sidewall of the emitter electrode is largerthan a portion of the N+ source region contacting the vertical sidewallof the emitter electrode.
 9. A power semiconductor device, comprising:trenches in a substrate comprising a first surface and a second surfaceopposite to the first surface; a gate insulating layer and a gateelectrode in each of the trenches; a P-type base region in thesubstrate; a P+ doped region and an N+ source region in the P-type baseregion; an interlayer insulating layer on the P+ doped region and the N+source region; and an emitter electrode contacting the N+ source region,wherein a portion of the P+ doped region contacts both a verticalsidewall of the emitter electrode and a bottom surface of the emitterelectrode.
 10. The power semiconductor device of claim 9, wherein aportion of the N+ source region contacts a vertical sidewall of theemitter electrode.
 11. The power semiconductor device of claim 10,wherein the portion of the P+ doped region contacting a verticalsidewall of the emitter electrode is larger than the portion of the N+source region contacting the vertical sidewall of the emitter electrode.12. The power semiconductor device of claim 9, further comprising: acollector region on the second surface of the substrate; and a drainelectrode on the collector region.